docs(design): remove SVG, use PNG logo only

SVG icon is no longer in use. public/logo.png (1024x1024 RGBA) is
the single logo asset. DESIGN.md updated accordingly: SVG snippet
removed, wordmark pattern and <head> references updated to PNG.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

node_modules/tailwindcss/plugin.d.ts

@@ -0,0 +1,11 @@
+import type { Config, PluginCreator } from './types/config'
+type Plugin = {
+  withOptions<T>(
+    plugin: (options: T) => PluginCreator,
+    config?: (options: T) => Partial<Config>
+  ): { (options: T): { handler: PluginCreator; config?: Partial<Config> }; __isOptionsFunction: true }
+  (plugin: PluginCreator, config?: Partial<Config>): { handler: PluginCreator; config?: Partial<Config> }
+}
+
+declare const plugin: Plugin
+export = plugin